Ser. MelaxospermEjE. Fnm. Fucea. 



Plate XLVII. 



FUCUS SERKATUS, Linn. 



Gen.Chah. Frond linear, either flat, compressed, or cylindrical, dichotomous 

 (rarely pinnated), coriaceous. Air-vessels, when present, innate, 

 simple. Receptacles either terminal, or lateral, filled with mucus 

 traversed by a network of jointed fibres, pierced by numerous pores, 

 which communicate with immersed spherical conceptacles, containing 

 parietal spores, or antkeridia, or both. Fucus (L), (j>vkos, a seaweed. 



Fucus serratus ; frond plane, dichotomous, mid-ribbed, serrated, without 



air-vessels ; receptacles flat, terminating the branches, serrated. 



Fucus serratus, Linn. Sp. PL p. 1626. Fl. Lap. p. 365. Fl. Snec. p. 430. 

 Huds. Fl. Ang. p. 576. Light/. Fl. Scot. vol. ii. p. 902. Stack. Ner. Brit. 

 p. 2. 1. 1. Turn. Syn. vol. i. p. 110. Hist. t. 90. E. Bot. 1. 1221. Lyngb. 

 Hyd. p. 5. t. 1. Ag. Sp. Alg. vol. i. p. 95. Syst. p. 278. Hook Fl. Scot. 

 part 2. p. 95. Grev. Fl. Eclin. p. 284. Alg. Brit. p. 15. Hook. Br. Fl. 

 vol. ii. p. 267. Harv. in Mack. Fl. Hib. part 3. p. 169. Wyatt, Alg. Damn. 

 no. 2. Endl. 3. Suppl. p. 29. Kutz. Fhyc. Gen. p. 352. 



Hab. On rocky sea shores, clothing the rocks at half-tide level. Perennial. 

 Winter and Spring. Very common. 



Geogr. Distr. Atlantic coasts of Europe from Norway to Spain. Baltic Sea. 

 Greenland, Lyngb. Coast of Piedmont, Allioni (doubtful). 



Descr. Root a hard, conical disc. Frond from two to six feet long, and from 

 half an inch to two inches in breadth, linear, traversed by a strong, thick 

 mid-rib, regularly dichotomous, the margin sharply serrated, or occasionally 

 laciniated. Mid-rib thickened at the forking. Vesicles none. Receptacles 

 flat, terminating the branches, of which they are merely prolongations, 

 slightly altered in structure, and containing numerous immersed conceptacles 

 communicating with external pores, These conceptacles are spherical, hollow, 

 and seem to be formed by an inflexion of the periphery of the frond. In 

 some individuals they produce from all parts of their inner surface, nume- 

 rous obovate spores, which finally separate into eight distinct sporules, and 

 are surrounded by filamentous processes. In other individuals the place of 

 the spores is occupied by tufts of much-branched, jointed filaments, which 

 produce an abundance of elliptical cellules, filled with numerous, bright- 

 orange, vivaccous corpuscles or zoospores, which eventually issue from their 

 cases and swim about, with a rapid motion, resembling the voluntary move- 

 ment of animalcules. These cellule* are called antheridia, and their con- 

 tained zoospores supposed to fulfil the office of pollen. They are never 

 found on the same plant as the spores, the species being -trietlv dioBcious. 



Fucus serratus abounds on all the Atlantic shores of Europe. 

 and probably extends to the eastern shores of America, but is not 

 found, according to J. Agardh, in the Mediterranean Sea, although 



i. 



